Question: A jar contains $4$ red balls, $11$ green balls, and $6$ blue balls. If a ball is randomly chosen, what is the probability that it is not green?
Solution: There are $4 + 11 + 6 = 21$ balls in the jar. There are $11$ green balls. That means $21 - 11 = 10$ are not green. The probability is $ \frac{10}{21}$.